Amethyst
Quartz var. Amethyst · Semi-Precious Gemstone
Crystal System
Trigonal; Hexagonal prisms terminated by rhombohedrons; typically found as geode linings or massive tumbles
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with traces of Iron (Fe3+)
Formation Process
Hydrothermal; forms in cavities (geodes) of volcanic rock from silica-rich water at low to moderate temperatures
About This Crystal
Deep purple to violet color, translucent to transparent, vitreous luster, often appearing as a rounded tumbled stone with smooth, reflective surfaces
Physical Characteristics
Purple body color; white streak; no true cleavage; conchoidal fracture; specific gravity 2.65; greenish fluorescence under shortwave UV occasionally visible
Optical Properties
Refractive index 1.544–1.553; double refraction; weak pleochroism (purple/reddish-purple); no dispersion; lacks chatoyancy
Hardness & Durability
Origin Region
Brazil, Uruguay, Madagascar, Zambia, and South Korea
Hardness & Durability
7.0 on Mohs scale; good toughness; stable but sensitive to heat; highly wearable in all types of jewelry
Care & Maintenance
Clean with warm soapy water; avoid ultrasonic cleaners and steam; store away from direct sunlight to prevent color fading over time
Rarity & Value
Common; value depends on color saturation (deeper purple is higher value) and clarity; heat treatment is common to turn it into Citrine color
Special Characteristics
Color originates from irradiation resulting from iron impurities in the quartz lattice; may show color zoning (darker and lighter stripes)
Lore & History
Historically used by Ancient Greeks to prevent intoxication; symbol of royalty and piety in Middle Ages; associated with the Crown Chakra and sobriety